In his twenty years in the Navy between 1954 and 1974, David Dickens spent much of his time aboard submarines, at first attracted by the extra pay he could earn. He saw the Navy transition from diesel to nuclear power and became such an expert in the latter that he taught other sailors how to operate the new systems. During the Vietnam War, his sub did photographic patrols along the coast and also launched rubber life rafts manned by special operations sailors. Dickens provides a handy guide to how a submarine achieves buoyancy and the basic differences in the two kinds of power that propelled his various boats.